Colombian President Juan Manuel Santos and others want to talk about what they call the failed war on drugs, as President Obama tries to focus on economic ties.

President Obama appears on a screen at the Summit of the Americas in Cartagena,… (Fernando Vergara, Associated…)

CARTAGENA, Colombia — President Obama sought Saturday to emphasize the robust economic relationship between the United States and Latin America, and he flatly ruled out legalizing drugs as a way to combat the illegal trafficking that has ravaged the region.

Facing calls at a regional summit to consider decriminalization, Obama said he is open to a debate about drug policy, but he believes that legalization could lead to greater problems in countries hardest hit by drug-fueled violence.

"Legalization is not the answer," Obama told other hemispheric leaders at the two-day Summit of the Americas.

"The capacity of a large-scale drug trade to dominate certain countries if they were allowed to operate legally without any constraint could be just as corrupting, if not more corrupting, than the status quo," he said.

Obama told Colombian President Juan Manuel Santos, host of the summit, that he is willing to discuss whether American drug laws are "doing more harm than good in certain places."

Santos wants the 33 countries participating in the summit to consider alternatives to what many leaders consider the failed war on drugs, possibly including regulating marijuana and even cocaine the way that alcohol and tobacco are.

Other leaders also have urged such a dialogue despite the political discomfort it may cause Obama in an election year.

"In spite of all the efforts, the illicit drug business is still buoyant, drug addiction in all countries is a serious public health issue, and drug trafficking is still the main provider of funding for violence and terrorism," Santos said. "An in-depth discussion around this topic is needed, without any biases or dogmas, taking into consideration the different scenarios and possible alternatives to more effectively face this challenge."

The focus on drug trafficking — as well as a scandal involving alleged misconduct by Secret Service agents and military personnel — threatened to overshadow Obama's main mission in Colombia: touting the benefits of a strong economic relationship across the hemisphere.

"I think that oftentimes in the press the attention in summits like this ends up focusing on, 'Where are the controversies?'" Obama said during a morning session.

Some of those issues seem "caught in a time warp, going back to the 1950s and gunboat diplomacy and Yanquis and the Cold War, and this and that and the other," he said. "That's not the world we live in today."

He praised a recently negotiated trade agreement with Colombia as a "win-win."

He did not say whether Colombia has met the terms of a labor rights plan that Congress set last year as a condition of passage of the agreement. The trade accord was strongly opposed by union leaders, who complained of the dangerous conditions facing members of organized labor in Colombia.

Obama avoided confrontations with the region's most anti-American leaders. Cuba'spresident, Raul Castro, was not invited to the summit. And Venezuela's president, Hugo Chavez, who is highly critical of U.S. policy, abruptly canceled plans to attend.

Chavez, who suffers from cancer, will travel to Cuba instead for radiation therapy, Foreign Minister Nicolas Maduro said on state TV.